// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package ethstats implements the network stats reporting service.
package ptnstats

import (
	//"context"
	"encoding/json"
	"errors"
	"fmt"
	"math/big"
	//"net"
	"regexp"
	"runtime"
	"strconv"
	//"strings"
	"time"

	"github.com/palletone/go-palletone/common"
	//"github.com/palletone/go-palletone/common/mclock"
	//"github.com/palletone/go-palletone/consensus"
	"github.com/ethereum/go-ethereum/event"
	"github.com/palletone/go-palletone/common/log"
	"github.com/palletone/go-palletone/common/p2p"
	"github.com/palletone/go-palletone/common/rpc"
	"github.com/palletone/go-palletone/dag/modules"
	"github.com/palletone/go-palletone/ptn"
	"golang.org/x/net/websocket"
)

const (
	// historyUpdateRange is the number of blocks a node should report upon login or
	// history request.
	historyUpdateRange = 50

	// txChanSize is the size of channel listening to TxPreEvent.
	// The number is referenced from the size of tx pool.
	txChanSize = 4096
	// chainHeadChanSize is the size of channel listening to ChainHeadEvent.
	chainHeadChanSize = 10
)

type txPool interface {
	// SubscribeTxPreEvent should return an event subscription of
	// TxPreEvent and send events to the given channel.
	SubscribeTxPreEvent(chan<- modules.TxPreEvent) event.Subscription
}

//type blockChain interface {
//	SubscribeChainHeadEvent(ch chan<- coredata.ChainHeadEvent) event.Subscription
//}

// Service implements an PalletOne netstats reporting daemon that pushes local
// chain statistics up to a monitoring server.
type Service struct {
	server *p2p.Server    // Peer-to-peer server to retrieve networking infos
	ptn    *ptn.PalletOne // Full PalletOne service if monitoring a full node
	//engine consensus.Engine // Consensus engine to retrieve variadic block fields//would recover

	node string // Name of the node to display on the monitoring page
	pass string // Password to authorize access to the monitoring page
	host string // Remote address of the monitoring service

	pongCh chan struct{} // Pong notifications are fed into this channel
	histCh chan []uint64 // History request block numbers are fed into this channel
}

type LightEthereum struct{}

// New returns a monitoring service ready for stats reporting.
func New(url string, ptnServ *ptn.PalletOne) (*Service, error) {
	// Parse the netstats connection url
	re := regexp.MustCompile("([^:@]*)(:([^@]*))?@(.+)")
	parts := re.FindStringSubmatch(url)
	if len(parts) != 5 {
		return nil, fmt.Errorf("invalid netstats url: \"%s\", should be nodename:secret@host:port", url)
	}
	// Assemble and return the stats service
	/*would recover
	var engine consensus.Engine
	if ptnServ != nil {
		engine = ptnServ.Engine()
	} else {
		engine = lesServ.Engine()
	}*/
	return &Service{
		ptn: ptnServ,
		//engine: engine,//would recover
		node:   parts[1],
		pass:   parts[3],
		host:   parts[4],
		pongCh: make(chan struct{}),
		histCh: make(chan []uint64, 1),
	}, nil
}

// Protocols implements node.Service, returning the P2P network protocols used
// by the stats service (nil as it doesn't use the devp2p overlay network).
func (s *Service) Protocols() []p2p.Protocol { return nil }
func (s *Service) GenesisHash() common.Hash {
	return common.Hash{}
}
func (s *Service) CorsProtocols() []p2p.Protocol { return nil }

// APIs implements node.Service, returning the RPC API endpoints provided by the
// stats service (nil as it doesn't provide any user callable APIs).
func (s *Service) APIs() []rpc.API { return nil }

// Start implements node.Service, starting up the monitoring and reporting daemon.
func (s *Service) Start(server *p2p.Server, corss *p2p.Server) error {
	s.server = server
	go s.loop()

	log.Info("Stats daemon started")
	return nil
}

// Stop implements node.Service, terminating the monitoring and reporting daemon.
func (s *Service) Stop() error {
	log.Info("Stats daemon stopped")
	return nil
}

// loop keeps trying to connect to the netstats server, reporting chain events
// until termination.
func (s *Service) loop() {
	/*
		// Subscribe to chain events to execute updates on
		var blockchain blockChain
		var txpool txPool
		if s.ptn != nil {
			blockchain = s.ptn.BlockChain()
			txpool = s.ptn.TxPool()
		} else {
			blockchain = s.les.BlockChain()
			txpool = s.les.TxPool()
		}

		chainHeadCh := make(chan core.ChainHeadEvent, chainHeadChanSize)
		headSub := blockchain.SubscribeChainHeadEvent(chainHeadCh)
		defer headSub.Unsubscribe()

		txEventCh := make(chan core.TxPreEvent, txChanSize)
		txSub := txpool.SubscribeTxPreEvent(txEventCh)
		defer txSub.Unsubscribe()

		// Start a goroutine that exhausts the subsciptions to avoid events piling up
		var (
			quitCh = make(chan struct{})
			headCh = make(chan *types.Block, 1)
			txCh   = make(chan struct{}, 1)
		)
		go func() {
			var lastTx mclock.AbsTime

		HandleLoop:
			for {
				select {
				// Notify of chain head events, but drop if too frequent
				case head := <-chainHeadCh:
					select {
					case headCh <- head.Block:
					default:
					}

				// Notify of new transaction events, but drop if too frequent
				case <-txEventCh:
					if time.Duration(mclock.Now()-lastTx) < time.Second {
						continue
					}
					lastTx = mclock.Now()

					select {
					case txCh <- struct{}{}:
					default:
					}

				// node stopped
				case <-txSub.Err():
					break HandleLoop
				case <-headSub.Err():
					break HandleLoop
				}
			}
			close(quitCh)
		}()
		// Loop reporting until termination
		for {
			// Resolve the URL, defaulting to TLS, but falling back to none too
			path := fmt.Sprintf("%s/api", s.host)
			urls := []string{path}

			if !strings.Contains(path, "://") { // url.Parse and url.IsAbs is unsuitable (https://github.com/golang/go/issues/19779)
				urls = []string{"wss://" + path, "ws://" + path}
			}
			// Establish a websocket connection to the server on any supported URL
			var (
				conf *websocket.Config
				conn *websocket.Conn
				err  error
			)
			for _, url := range urls {
				if conf, err = websocket.NewConfig(url, "http://localhost/"); err != nil {
					continue
				}
				conf.Dialer = &net.Dialer{Timeout: 5 * time.Second}
				if conn, err = websocket.DialConfig(conf); err == nil {
					break
				}
			}
			if err != nil {
				log.Warn("Stats server unreachable", "err", err)
				time.Sleep(10 * time.Second)
				continue
			}
			// Authenticate the client with the server
			if err = s.login(conn); err != nil {
				log.Warn("Stats login failed", "err", err)
				conn.Close()
				time.Sleep(10 * time.Second)
				continue
			}
			go s.readLoop(conn)

			// Send the initial stats so our node looks decent from the get go
			if err = s.report(conn); err != nil {
				log.Warn("Initial stats report failed", "err", err)
				conn.Close()
				continue
			}
			// Keep sending status updates until the connection breaks
			fullReport := time.NewTicker(15 * time.Second)

			for err == nil {
				select {
				case <-quitCh:
					conn.Close()
					return

				case <-fullReport.C:
					if err = s.report(conn); err != nil {
						log.Warn("Full stats report failed", "err", err)
					}
				case list := <-s.histCh:
					if err = s.reportHistory(conn, list); err != nil {
						log.Warn("Requested history report failed", "err", err)
					}
				case head := <-headCh:
					if err = s.reportBlock(conn, head); err != nil {
						log.Warn("Block stats report failed", "err", err)
					}
					if err = s.reportPending(conn); err != nil {
						log.Warn("Post-block transaction stats report failed", "err", err)
					}
				case <-txCh:
					if err = s.reportPending(conn); err != nil {
						log.Warn("Transaction stats report failed", "err", err)
					}
				}
			}
			// Make sure the connection is closed
			conn.Close()
		}*/
}

// readLoop loops as long as the connection is alive and retrieves data packets
// from the network socket. If any of them match an active request, it forwards
// it, if they themselves are requests it initiates a reply, and lastly it drops
// unknown packets.
func (s *Service) readLoop(conn *websocket.Conn) {
	// If the read loop exists, close the connection
	defer conn.Close()

	for {
		// Retrieve the next generic network packet and bail out on error
		var msg map[string][]interface{}
		if err := websocket.JSON.Receive(conn, &msg); err != nil {
			log.Warn("Failed to decode stats server message", "err", err)
			return
		}
		log.Trace("Received message from stats server", "msg", msg)
		if len(msg["emit"]) == 0 {
			log.Warn("Stats server sent non-broadcast", "msg", msg)
			return
		}
		command, ok := msg["emit"][0].(string)
		if !ok {
			log.Warn("Invalid stats server message type", "type", msg["emit"][0])
			return
		}
		// If the message is a ping reply, deliver (someone must be listening!)
		if len(msg["emit"]) == 2 && command == "node-pong" {
			select {
			case s.pongCh <- struct{}{}:
				// Pong delivered, continue listening
				continue
			default:
				// Ping routine dead, abort
				log.Warn("Stats server pinger seems to have died")
				return
			}
		}
		// If the message is a history request, forward to the event processor
		if len(msg["emit"]) == 2 && command == "history" {
			// Make sure the request is valid and doesn't crash us
			request, ok := msg["emit"][1].(map[string]interface{})
			if !ok {
				log.Warn("Invalid stats history request", "msg", msg["emit"][1])
				s.histCh <- nil
				continue // Ptnstats sometime sends invalid history requests, ignore those
			}
			list, ok := request["list"].([]interface{})
			if !ok {
				log.Warn("Invalid stats history block list", "list", request["list"])
				return
			}
			// Convert the block number list to an integer list
			numbers := make([]uint64, len(list))
			for i, num := range list {
				n, ok := num.(float64)
				if !ok {
					log.Warn("Invalid stats history block number", "number", num)
					return
				}
				numbers[i] = uint64(n)
			}
			select {
			case s.histCh <- numbers:
				continue
			default:
			}
		}
		// Report anything else and continue
		log.Info("Unknown stats message", "msg", msg)
	}
}

// nodeInfo is the collection of metainformation about a node that is displayed
// on the monitoring page.
type nodeInfo struct {
	Name     string `json:"name"`
	Node     string `json:"node"`
	Port     int    `json:"port"`
	Network  string `json:"net"`
	Protocol string `json:"protocol"`
	API      string `json:"api"`
	Os       string `json:"os"`
	OsVer    string `json:"os_v"`
	Client   string `json:"client"`
	History  bool   `json:"canUpdateHistory"`
}

// authMsg is the authentication infos needed to login to a monitoring server.
type authMsg struct {
	Id     string   `json:"id"`
	Info   nodeInfo `json:"info"`
	Secret string   `json:"secret"`
}

// login tries to authorize the client at the remote server.
func (s *Service) login(conn *websocket.Conn) error {
	// Construct and send the login authentication
	infos := s.server.NodeInfo()

	var network, protocol string
	if info := infos.Protocols["ptn"]; info != nil {
		network = fmt.Sprintf("%d", info.(*ptn.NodeInfo).Network)
		protocol = fmt.Sprintf("ptn/%d", ptn.ProtocolVersions[0])
	} else {
		//network = fmt.Sprintf("%d", infos.Protocols["les"].(*les.NodeInfo).Network)
		//protocol = fmt.Sprintf("les/%d", les.ClientProtocolVersions[0])
	}
	auth := &authMsg{
		Id: s.node,
		Info: nodeInfo{
			Name:     s.node,
			Node:     infos.Name,
			Port:     infos.Ports.Listener,
			Network:  network,
			Protocol: protocol,
			API:      "No",
			Os:       runtime.GOOS,
			OsVer:    runtime.GOARCH,
			Client:   "0.1.1",
			History:  true,
		},
		Secret: s.pass,
	}
	login := map[string][]interface{}{
		"emit": {"hello", auth},
	}
	if err := websocket.JSON.Send(conn, login); err != nil {
		return err
	}
	// Retrieve the remote ack or connection termination
	var ack map[string][]string
	if err := websocket.JSON.Receive(conn, &ack); err != nil || len(ack["emit"]) != 1 || ack["emit"][0] != "ready" {
		return errors.New("unauthorized")
	}
	return nil
}

// report collects all possible data to report and send it to the stats server.
// This should only be used on reconnects or rarely to avoid overloading the
// server. Use the individual methods for reporting subscribed events.
func (s *Service) report(conn *websocket.Conn) error {
	if err := s.reportLatency(conn); err != nil {
		return err
	}
	//	if err := s.reportBlock(conn, nil); err != nil {
	//		return err
	//	}
	if err := s.reportPending(conn); err != nil {
		return err
	}
	if err := s.reportStats(conn); err != nil {
		return err
	}
	return nil
}

// reportLatency sends a ping request to the server, measures the RTT time and
// finally sends a latency update.
func (s *Service) reportLatency(conn *websocket.Conn) error {
	// Send the current time to the ethstats server
	start := time.Now()

	ping := map[string][]interface{}{
		"emit": {"node-ping", map[string]string{
			"id":         s.node,
			"clientTime": start.String(),
		}},
	}
	if err := websocket.JSON.Send(conn, ping); err != nil {
		return err
	}
	// Wait for the pong request to arrive back
	select {
	case <-s.pongCh:
		// Pong delivered, report the latency
	case <-time.After(5 * time.Second):
		// Ping timeout, abort
		return errors.New("ping timed out")
	}
	latency := strconv.Itoa(int((time.Since(start) / time.Duration(2)).Nanoseconds() / 1000000))

	// Send back the measured latency
	log.Trace("Sending measured latency to ethstats", "latency", latency)

	stats := map[string][]interface{}{
		"emit": {"latency", map[string]string{
			"id":      s.node,
			"latency": latency,
		}},
	}
	return websocket.JSON.Send(conn, stats)
}

// blockStats is the information to report about individual blocks.
type blockStats struct {
	Number     *big.Int       `json:"number"`
	Hash       common.Hash    `json:"hash"`
	ParentHash common.Hash    `json:"parentHash"`
	Timestamp  *big.Int       `json:"timestamp"`
	Miner      common.Address `json:"miner"`
	GasUsed    uint64         `json:"gasUsed"`
	GasLimit   uint64         `json:"gasLimit"`
	Diff       string         `json:"difficulty"`
	TotalDiff  string         `json:"totalDifficulty"`
	Txs        []txStats      `json:"transactions"`
	TxHash     common.Hash    `json:"transactionsRoot"`
	Root       common.Hash    `json:"stateRoot"`
	Uncles     uncleStats     `json:"uncles"`
}

// txStats is the information to report about individual transactions.
type txStats struct {
	Hash common.Hash `json:"hash"`
}

// uncleStats is a custom wrapper around an uncle array to force serializing
// empty arrays instead of returning null for them.
type uncleStats []*modules.Header

func (s uncleStats) MarshalJSON() ([]byte, error) {
	if uncles := ([]*modules.Header)(s); len(uncles) > 0 {
		return json.Marshal(uncles)
	}
	return []byte("[]"), nil
}

// reportHistory retrieves the most recent batch of blocks and reports it to the
// stats server.
func (s *Service) reportHistory(conn *websocket.Conn, list []uint64) error {
	/*
		// Figure out the indexes that need reporting
		indexes := make([]uint64, 0, historyUpdateRange)
		if len(list) > 0 {
			// Specific indexes requested, send them back in particular
			indexes = append(indexes, list...)
		} else {
			// No indexes requested, send back the top ones
			var head int64
			if s.ptn != nil {
				head = s.ptn.BlockChain().CurrentHeader().Number.Int64()
			} else {
				head = s.les.BlockChain().CurrentHeader().Number.Int64()
			}
			start := head - historyUpdateRange + 1
			if start < 0 {
				start = 0
			}
			for i := uint64(start); i <= uint64(head); i++ {
				indexes = append(indexes, i)
			}
		}
		// Gather the batch of blocks to report
		history := make([]*blockStats, len(indexes))
		for i, number := range indexes {
			// Retrieve the next block if it's known to us
			var block *types.Block
			if s.ptn != nil {
				block = s.ptn.BlockChain().GetBlockByNumber(number)
			} else {
				if header := s.les.BlockChain().GetHeaderByNumber(number); header != nil {
					block = types.NewBlockWithHeader(header)
				}
			}
			// If we do have the block, add to the history and continue
			if block != nil {
				history[len(history)-1-i] = s.assembleBlockStats(block)
				continue
			}
			// Ran out of blocks, cut the report short and send
			history = history[len(history)-i:]
			break
		}
		// Assemble the history report and send it to the server
		if len(history) > 0 {
			log.Trace("Sending historical blocks to ethstats", "first", history[0].Number, "last", history[len(history)-1].Number)
		} else {
			log.Trace("No history to send to stats server")
		}
		stats := map[string]interface{}{
			"id":      s.node,
			"history": history,
		}
		report := map[string][]interface{}{
			"emit": {"history", stats},
		}
		return websocket.JSON.Send(conn, report)
	*/
	return nil
}

// pendStats is the information to report about pending transactions.
type pendStats struct {
	Pending int `json:"pending"`
}

// reportPending retrieves the current number of pending transactions and reports
// it to the stats server.
func (s *Service) reportPending(conn *websocket.Conn) error {
	/*
		// Retrieve the pending count from the local blockchain
		var pending int
		if s.ptn != nil {
			pending, _ = s.ptn.TxPool().Stats()
		} else {
			pending = s.les.TxPool().Stats()
		}
		// Assemble the transaction stats and send it to the server
		log.Trace("Sending pending transactions to ethstats", "count", pending)

		stats := map[string]interface{}{
			"id": s.node,
			"stats": &pendStats{
				Pending: pending,
			},
		}
		report := map[string][]interface{}{
			"emit": {"pending", stats},
		}
		return websocket.JSON.Send(conn, report)
	*/
	return nil
}

// nodeStats is the information to report about the local node.
type nodeStats struct {
	Active   bool `json:"active"`
	Syncing  bool `json:"syncing"`
	Mining   bool `json:"mining"`
	Hashrate int  `json:"hashrate"`
	Peers    int  `json:"peers"`
	GasPrice int  `json:"gasPrice"`
	Uptime   int  `json:"uptime"`
}

// reportPending retrieves various stats about the node at the networking and
// mining layer and reports it to the stats server.
func (s *Service) reportStats(conn *websocket.Conn) error {
	/*
		// Gather the syncing and mining infos from the local miner instance
		var (
			mining   bool
			hashrate int
			syncing  bool
			gasprice int
		)
		if s.ptn != nil {
			mining = s.ptn.Miner().Mining()
			hashrate = int(s.ptn.Miner().HashRate())

			sync := s.ptn.Downloader().Progress()
			syncing = s.ptn.BlockChain().CurrentHeader().Number.Uint64() >= sync.HighestBlock

			price, _ := s.ptn.ApiBackend.SuggestPrice(context.Background())
			gasprice = int(price.Uint64())
		} else {
			sync := s.les.Downloader().Progress()
			syncing = s.les.BlockChain().CurrentHeader().Number.Uint64() >= sync.HighestBlock
		}
		// Assemble the node stats and send it to the server
		log.Trace("Sending node details to ethstats")

		stats := map[string]interface{}{
			"id": s.node,
			"stats": &nodeStats{
				Active:   true,
				Mining:   mining,
				Hashrate: hashrate,
				Peers:    s.server.PeerCount(),
				GasPrice: gasprice,
				Syncing:  syncing,
				Uptime:   100,
			},
		}
		report := map[string][]interface{}{
			"emit": {"stats", stats},
		}
		return websocket.JSON.Send(conn, report)
	*/
	return nil
}
